WO1999054145A1

WO1999054145A1 - Ink jet recording paper

Info

Publication number: WO1999054145A1
Application number: PCT/JP1999/001938
Authority: WO
Inventors: Yoshihiko Hibino; Koji Idei
Original assignee: Mitsubishi Paper Mills Limited
Priority date: 1998-04-21
Filing date: 1999-04-12
Publication date: 1999-10-28
Also published as: ID26287A; US6969445B1; KR100403534B1; KR20010042754A; CN1193897C; AU3169299A; EP1086825B1; EP1086825A4; DE69920218D1; DE69920218T2; EP1086825A1; CN1298351A

Abstract

Ink jet recording paper which is so-called plain paper with no coating using a pigment applied to its recording face and is excellent in recorded image density, color reproducibility and waterproofness and surface strength at the printed portion; specifically, ink jet recording paper obtained by applying a coating liquid containing a fluorescent whitening agent, a water soluble binder and a cationic polymer fixer to neutral base paper using wood pulp as a main material; specifically, ink jet recording paper, wherein an ISO brightness of coated paper as measured by a measuring method specified in JIS P-8148 with a xenon flash tube used as a light source is not less than 95 % and its fluorescent intensity is 7 to 15 %, the ink jet recording paper being machine-made using calcium carbonate as a filler and containing 5 to 20 % of base paper ash component through a specified treatment and a mixture in a specified ratio of a specified fluorescent whitening agent and a specified cationic polymer fixer.

Description

Description Inkjet recording paper

Technical field

The present invention relates to an ink jet recording sheet for recording in color using a water-soluble ink. More specifically, the present invention relates to a so-called plain paper type ink jet recording paper in which the recording surface is not coated with a pigment, and in particular, the image recorded by increasing the whiteness of the paper with a fluorescent whitening agent. The present invention relates to an ink jet recording paper having excellent image density and color reproducibility, and excellent water resistance and surface strength of a printed portion.

Background art

The ink jet recording method is a method in which ink is directly ejected onto recording paper, and has attracted attention as a recording method that has a lower running cost, is quieter, and is easier to perform color recording than conventional recording apparatuses. The ink used in such a recording method is water-based ink in terms of safety and printing characteristics, and the recording paper absorbs the ink quickly and causes overflow of the ink even if there are overlapping inks of different colors. That the ink dots are not spread properly, that the dot shape is close to a perfect circle, that the dot edges are sharp, that the dot density is high, and that dot It is required that the ISO whiteness is high enough to make the contrast of the photo stand out.

As the recording paper used in the above-mentioned ink jet recording system, in order to meet the above-mentioned conventional requirements, for example, Japanese Patent Application Laid-Open No. 59-35997 and Japanese Patent Application Laid-Open No. 1-135628 The use of a special coated paper as disclosed in U.S. Pat. On the other hand, in the field of monochrome recording and business color recording, it is desired to use low-cost and versatile recording paper, that is, plain paper generally used in the electrophotographic recording apparatus field. .

In recent years, when neutral toner transfer paper, which is becoming the mainstream recording paper for electrophotographic recording devices, is used for the ink jet recording paper, it can be used as base paper. The amount of filler that can be used was limited, and paper with high color reproducibility and high whiteness in color printing was not obtained compared to full-color coated paper. Furthermore, the so-called plain paper type inkjet recording paper, which has not been coated with a pigment on the recording surface that has been proposed so far, focuses on the ability to perform ink jet recording. The problem of water resistance was not improved at all.

An object of the present invention is to improve the conventional problems in the above technical field. This is a so-called plain paper type color ink jet recording paper that does not have a coating on the recording surface that uses pigments.It has excellent surface strength, and in particular, has excellent water resistance of the recorded image and enhances the whiteness of the ISO. Accordingly, an object of the present invention is to provide an ink jet recording sheet excellent in image density of a recorded image and color reproducibility.

Disclosure of the invention

The above object is achieved by the present invention described below.

That is, the ink jet recording paper of the first invention is obtained by coating a neutral base paper mainly made of wood pulp with a coating liquid mainly containing a fluorescent whitening agent, a water-soluble binder and a cationic polymer fixing agent. The ink jet recording paper was obtained by using the xenon flash lamp of the coated paper as the light source and the ISO whiteness measured by the measurement method specified in JISP-8148 was 95. % Or more, and the fluorescence intensity is 7 to 5%.

The ink jet recording paper of the second invention is the same as that of the first invention, except that calcium carbonate is used as a filler for the neutral base paper, and the incineration is performed at 500 ° C. for 4 hours. The base paper ash content according to 126 is 5 to 20%.

In an ink jet recording paper according to a third aspect, in the first aspect, the fluorescent whitening agent of the coating solution is a diaminostilbene-disulfonic acid derivative (A), and the cationic polymer fixing agent is polyvinyl alcohol. It is a one-strength thione monomer graft polymer (B), and the mixing ratio A: B of the solid coating amount is 1: 6 to 2: 3. Further, in the ink jet recording paper according to the first to third aspects, the coating liquid is preferably applied using an on-machine size press of a paper machine. Further, in the ink jet recording paper according to the first to fourth inventions, preferably, the wood pulp contains waste paper pulp.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the inkjet recording paper of the present invention will be described in detail.

The present inventors first studied the relationship between the ISO whiteness of the ink jet recording paper of the present invention and the printing characteristics of the ink jet recording apparatus.

The plain paper type ink jet recording paper does not have an ink absorbing layer unlike the so-called coated paper type, so the base paper is used as the ink absorbing layer. Therefore, the whiteness of the base paper affects the printing characteristics of the ink jet recording paper. The whiter the base paper, the higher the contrast of the printed matter, and the higher the print quality.

However, the whiteness of the sample containing the fluorescent whitening agent does not match the luminous whiteness because the Hunter-One Whiteness specified in JISP-8123 has been used for the evaluation of the whiteness. In many cases. This is because in Hunter whiteness, the illuminating light illuminates the filament-type lamp with light that has passed through a blue filter, and the light in the wavelength region that excites the fluorescent whitening agent (mainly light in the ultraviolet region) is large. It is probable that the reason was that the cut was made at the same time. With ISO whiteness, white light from an illumination light source is diffusely illuminated using an integrating sphere. If a xenon flash lamp is used as the illumination light source, light in the wavelength range that excites the fluorescent brightener is included, so that a numerical expression close to luminous whiteness becomes possible.

As a result of comparing and examining the relationship between the Iso whiteness of the ink jet recording paper of the present invention and the printing characteristics of the ink jet recording apparatus, it was found that the whiteness of the sample and the printing characteristics, particularly, the image density after printing, and the image reproducibility. And a good correlation was found between them. Then, when the ISO whiteness of the recording paper used in the ink jet recording apparatus was 95% or more, it was found that the image density when printed by the ink jet recording apparatus and the balance of the image reproducibility were good. Invented the ink jet recording paper. In order to improve only the visual whiteness, the pulp fiber is given a bluish purple color, which is the color of yellow, by baking the sample, which has been widely used in the past. , And in some cases even more bluish, giving the illusion of improved whiteness, but with the problem that the brightness was considerably reduced.

In order to improve the printing characteristics of the ink jet recording paper, an ISO whiteness of 95 is used by using a fluorescent whitening agent. Must be at least / ₀ . The fluorescent whitening agent on the pulp fiber absorbs ultraviolet light in daylight and emits fluorescence of 400 to 500 nm, so it supplements the reflected light on the short wavelength side of the visible part. As a result of the bluing being performed without a decrease in lightness, the whiteness appears to be further improved to the naked eye. Therefore, brightening with an optical brightener is different from bleaching, which chemically removes coloring substances and stains from materials. As a result, a remarkable whitening effect that cannot be achieved in the bleaching step can be obtained. With color ink jet recording paper, if the ISO whiteness is less than 95%, the visual whiteness is insufficient, and the print quality is poor with poor image reproducibility. Therefore, in consideration of the printing characteristics of the ink jet recording paper and the whiteness upon printing, the ISO whiteness is desirably 95% or more.

In order to improve Isofi chromaticity, in addition to selecting a material having high whiteness as a raw material for papermaking, a fluorescent whitening agent can be applied from the above mechanism. The effect is recognized when the amount of the fluorescent whitening agent is large, but the effect gradually becomes saturated, eventually causing a phenomenon called overdyeing, and conversely, the whiteness decreases. In the present invention, it is preferable to express the fluorescence intensity other than the Iso whiteness. The fluorescence intensity is expressed as a difference between whiteness measured with illumination light including light in the ultraviolet region and whiteness measured with illumination light in which light in the ultraviolet region is cut by a UV filter. Preferably it is in the range of 5%. At less than 7%, the luminous whiteness is clearly reduced, and at 15% or more, the fluorescence is clearly saturated, which is not economically optimal.

Secondly, in the present invention, it is preferable to use calcium carbonate used in neutral paper as a filler used when making a base paper, since it can increase ISO whiteness. In addition, as ink jet recording paper, ink absorption It is preferable to use calcium carbonate from the viewpoints of improving yield and image density. Among the fillers that can be used for neutral base paper, calcium carbonate has high whiteness and high ink absorption. Furthermore, it is desirable that the ash content according to JISP-818 is 5 to 20% except that the incineration treatment is performed at 500 ° C for 4 hours. If the ash content of the paper is less than 5%, the suitability for ink jet recording is degraded in terms of ISO whiteness and opacity. On the other hand, when the ash content exceeds 20%, plain paper type paper is used for office paper as a versatile paper.On the other hand, an increase in the ash content causes a problem of paper dust from the recording paper edge. In addition, paper dust is generated due to a decrease in surface strength at the time of printing, causing problems such as shading.

Examples of the internal sizing agent used for making the base paper of the present invention include a neutral rosin-based sizing agent used for neutral papermaking, alkenyl succinic anhydride, an alkyl ketene dimer, and a petroleum resin-based sizing agent. Although it can be used, it is desirable to use a neutral sizing agent as an ink jet recording paper because it exhibits a uniform size effect even at a low size, as a measure against strike-through. Alkenyl succinic anhydride, alkyl ketene dimer, and other internal sizing agents commonly used in neutral papermaking require only small amounts due to their high sizing effect. Since it is inferior to a neutral gin sizing agent in terms of imparting size, it is not suitable as an internal sizing agent for ink jet recording paper. Even when the recording paper used in an electrophotographic transfer recording apparatus is diverted, it is desirable to use a neutral rosin sizing agent from the viewpoint of transportability.

In the stock, other paper-making materials such as various anionic, nonionic, cationic or amphoteric paper strength agents are used as long as the desired effects of the present invention are not impaired. An internal additive is appropriately selected and used as needed. For example, various starches and polyacrylamide, polyethyleneimine, polyamine, polyamide'polyamine, urea formalin resin, melamine formalin resin, vegetable gum, polybutyl alcohol, latex, polyethylene oxide, and polyamide resin One type or two or more types may be used in appropriate combination.

In addition, internal additives for papermaking such as dyes, fluorescent brighteners, pH regulators, defoamers, pitch control agents, and slim control agents can be added as appropriate according to the purpose. Noh.

In the papermaking method of the present invention, a paper machine known in the papermaking industry such as a fourdrinier paper machine, a twin-wire single paper machine, a combination paper machine, a round mesh paper machine, and a Yankee paper machine can be used as appropriate.

Thirdly, the most significant feature of the present invention is an ink jet recording paper in which the above-mentioned base paper is coated with a coating liquid containing a fluorescent whitening agent, a water-soluble binder and a cationic polymer fixing agent as main components. There is to be. By applying a water-soluble binder to the base paper, the strength of the base paper surface can be improved. In addition, the cationic polymer fixing agent is generally used as a recording paper for an ink jet recording apparatus and has an aionic group in order to impart water solubility. Water resistance of the printed image can be imparted.

However, when the focus is on only the fixing property of the ink, the cationic polymer fixing agent increases the cation intensity, and as a result, decreases the intensity of the fluorescent whitening agent, which is another feature of the present invention. Will be lost. The present inventors have intensively studied the relationship between the fixability of the ink and the decrease in the intensity of the fluorescent whitening agent for this cationic polymer binder, and found that the fluorescent whitening agent was a diaminostilbene-disulfonic acid derivative. (A), and the cationic polymer fixing agent is a polyvinyl alcohol-cationic monomer graft polymer (B), and the mixture ratio of the solid coating amount of both is A: B is 1 _: 6 to 2 _: 3, it was found that the combination of the expression of ISO whiteness and the water resistance of the ink-jet printed portion was compatible with each other, and the present invention was achieved. If the ratio of the fluorescent whitening agent is smaller than 1: 6, the ISO whiteness is reduced. If the ratio is larger than 2: 3, the water resistance of the printed ink jet printed portion is significantly deteriorated.

As the cationic polymer fixing agent in the present invention, a water-soluble dye, which is a dye component of an aqueous ink, is used in order to provide water resistance for suppressing ink bleeding due to water dripping or moisture absorption on recording paper. Use a monomer, oligomer or polymer of primary to tertiary amine or quaternary ammonium salt that forms an insoluble salt with sulfonic acid group, carboxyl group or amino group in direct dye or water-soluble acid dye Can be done. Specifically, dimethylamine'epiclorhydrin condensate, acrylamide.diallylamine copolymer, polybulamine copolymer, dicyandiamide, It is possible to add dimethyl 'diallylammonium chloride, polyvinyl alcohol-cation monomer graft polymer, etc., but the effect can be expressed when using polyvinyl alcohol mono-thione monomer graft polymer. It will be the best.

The fluorescent whitening agent in the present invention not only absorbs ultraviolet light in daylight and replenishes the reflected light on the short wavelength side of the visible region to perform bluing without a decrease in lightness, It must be excellent in light resistance, solubility, and dyeing properties. Specifically, diaminostilbene-disulfonic acid derivatives, oxazole derivatives, biphenyl derivatives, imidazole derivatives, coumarin derivatives, and pyrazoline derivatives are used.However, when pulp fibers are used, diaminostilbene-disulfonic acid derivatives are used. The effect is most likely to be expressed.

The water-soluble binder used here is, for example, polybutyl alcohol, silanol-modified polybutyl alcohol, biellite, oxidized starch, phosphorylated esterified starch, etherified starch, carboxymethylcellulose, or hydroxyxyl cellulose. Cellulose derivatives such as cellulose, casein, gelatin, soy protein, silyl-modified polybutyl alcohol, etc .; conjugated copolymer latexes such as maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate butadiene copolymer; A latex polymer latex such as a polymer or copolymer of acrylate and methacrylate, a polymer or copolymer of atrial acid and methacrylic acid; a latex polymer latex such as ethylene butyl acetate copolymer; To Or a functional group-modified polymer latex of a monomer containing a functional group such as a carboxyl group of these various polymers; an aqueous adhesive such as a thermosetting synthetic resin such as a melamine resin or a urea resin; a polymethyl methacrylate or a polyurethane resin One or more synthetic resin adhesives such as unsaturated polyester resin, vinyl chloride-biel acetate copolymer, polyvinyl butyral, and alkyd resin can be used. In addition, the use of a known natural or synthetic resin adhesive is not particularly limited.

In the present invention, one or more coloring dyes and coloring pigments can be added to the coating liquid in combination with a fluorescent whitening agent as an additive. The coloring dyes and coloring pigments can be used alone or as a mixture. However, for the purpose of the present invention, the wavelength of 580 to 60 It is preferable to use a brushing agent that absorbs yellow light of 0 nm. The coloring dye and coloring pigment used here are not particularly limited as long as they are generally used. More preferably, they are compatible with a water-soluble binder, have light resistance, and have uniform coloring during coating. From the viewpoint of properties, dioxazine pigments and lid-open cyanine pigments, which are anionic color pigments, are preferred.

In addition, other additives include surface sizing agents, pH regulators, thickeners, flow improvers, defoamers, foam inhibitors, release agents, foaming agents, penetrants, coloring dyes, coloring pigments, Of course, it is also possible to appropriately mix a fluorescent whitening agent, an ultraviolet absorber, a P preservative, an antifungal agent, an antioxidant, an inorganic conductive agent such as sodium chloride and potassium chloride, an organic conductive agent, and the like. .

Examples of an apparatus for applying a coating solution containing the above-described fluorescent whitening agent, water-soluble binder and cationic polymer fixing agent as main components by a size press in the present invention include a conventional size press and a gate roll size. A press or a film transfer type size press, a rod coater, a bill blade, a short dowel coater, or the like can be used. Among these coating devices, it is desirable to use a system in which the optical brightener can be uniformly applied to the paper layer on-machine, and an on-machine size press device is preferable. In addition, after coating, if necessary, finishing can be performed using a calendar device such as a machine calendar, heat calendar, super calendar, or soft calendar.

The coating amount in the present invention is not particularly limited. Although the coating depends on the size of the base paper, it is preferable to apply about 1 to 3 g / m ² as a solid content of the coating liquid to the base paper.

Examples of the wood pulp used for making the base paper of the present invention include waste paper pulp in addition to NBKPLBKP, NBSP, LBSP, GP, and TMP. These may be mixed and used at a ratio according to several purposes.

The raw materials for waste paper pulp referred to in the present invention include the above-mentioned white paper, white white, cream white, card, special white, medium white, and imitation as shown in the waste paper standard quality standard table of the Waste Paper Recycling Promotion Center. , Fair-skinned, kent, white art, extraordinary cut, separate upper cut, newspaper, magazine, etc. A more specific example is the information-related recording paper, a non-coated computer Printer recording paper such as recording paper, thermal paper, and pressure-sensitive paper; coated paper such as OA waste paper, art paper, coated paper, lightly coated paper, matte paper such as PPC recording paper, or high-quality paper, high-quality paper, Recycled paper and paperboard such as notebooks, stationery, wrapping paper, fancy paper, medium paper, newsprint paper, wrapped paper, super-hanging paper, imitation paper, pure white roll paper, uncoated paper such as milk carton, etc. Pulp paper, high-yield pulp-containing paper, and the like are used, but are not particularly limited regardless of printing, copying, printing, or non-printing. The ink jet recording paper of the present invention can be used not only as ink jet recording paper but also as office paper such as electrophotographic transfer paper, thermal transfer receiving paper, and printing paper.

Hereinafter, the present invention will be described in detail with reference to Examples. Note that the present invention is not limited to this. All parts and percentages below are by weight.

Examples 1 to 10 and Comparative Example:! ~ 8

First, base papers 1 to 6 were prepared according to the following composition.

Pulp; LBKP (freeness: 450m c. S. F) 100 parts Calcium carbonate (Okutama Kogyo; TP_121) 20 parts Neutral rosin sizing agent (Nippon PMC; CC-167) 0. 4 parts aluminum sulfate 1.4 parts amphoteric starch (NSC Japan; Cat 3210) 1.0 part dyes, "Sasso, -Riolet 57 L; BASF" 0 00096 parts retention aid (ARA) Co., Ltd .; Poid; Percoll 57) 0.025 parts Retention improver (Allide Colloid; Organozob O) 0.1 parts

Pulp; LBKP (freeness; 450 ml, c.s.f) 100 parts Calcium carbonate (Okutama Kogyo; TP-121) 10 parts Neutral rosin sizing agent (Nippon PMC; CC-167) 0 4 parts Aluminum sulfate 1.4 parts Optical brightener (Nippon Soda Co., Ltd .; Keikol BUL) 0.02 parts Amphoteric starch (NSC Japan; Cat 3210) 1.0 parts Dyes (manufactured by BASF; Ha-Sasso, -Lha'yoret 57 L) 0.00096 parts Retention improver (manufactured by Arido Co., Ltd .; Pacohol 57) 0.025 parts ; Organo Zorb O) 0.1 parts <base paper composition 3>

Pulp; high-white LBKP for photographic base paper (freeness: 450 ml, csf) 100 parts Tanolek (Kamitanorek; B Tanorek) 6 parts Gin sizing agent (/, Lima Chemicals; Harsize L-750) 0. 3 parts Aluminum sulfate 1.5 parts Optical brightener (Nippon Soda Co., Ltd .; Keiko BUL) 0.02 parts Cationic starch (Nippon NS C Co .; Cato 304) 0.3 parts Dyes (BASF Co., Ltd .; C) ', Sasso "-ruha" pellet 57 L) 0.00096 parts Retention improver (Kurita Kogyo Co .; High Holder 301) 0.03 parts <Base paper blend 4>

Pulp; high-white LBKP for photographic base paper (freeness: 450 ml, s.f) 100 parts Tanolek (manufactured by Kamitanorek; B Tanorek) 10 parts Rosin sizing agent (manufactured by Harima Chemicals; Harsize L-750) 0.3 Part Aluminum sulfate 1.5 parts Optical brightener (Nippon Soda Co., Ltd .; Keikol BUL) 0.02 parts Cationic starch (Nippon NS C Co .; Cat 304) 0.3 parts Dye (BASF Co., Ltd. Sasso, Luha, 'Yoretto 57 L) 0.00096 parts Retention improver (Kurita Kogyo Co .; High Holder 301) 0.03 parts <Base paper blend 5>

Pulp; high-white L BKP for photographic base paper (freeness; 450 ml, csf) 100 parts Tanolek (Kamitanorek; B Tanorek) 15 parts Rosin sizing agent (Harima Chemicals; Harsize L-750) 0.3 Part Aluminum sulfate 1.5 parts Fluorescent whitening agent (Nippon Soda Co., Ltd .; Caycol BUL) 0.02 parts Cationic starch (NSC Japan; Cato 304) 0.3 parts Dyes (BASF Co., Ltd .; Ha, Sasso) "-Luha" 57L) 0.00096 copies Yield improver (Kurita Kogyo; High Holder 301) 0.03 parts

Pulp; LBKP (freeness; 450 ml, csf) 100 parts Calcium carbonate (Okutama Kogyo; TP-121) 20 parts Neutral rosin sizing agent (3 PMC; CC_167) 0 4 parts Aluminum sulfate 1.4 parts Optical brightener (Nippon Soda Co., Ltd .; Keikol BUL) 1.0 parts Amphoteric starch (NSC Japan; Cat 3210) 1.0 parts Dye (BASF products; C) Sazo "-Ruha, Yoretto 57 L) 0 00096 parts Retention improver (manufactured by Arido Co., Ltd .; Percoll 57) 0.025 parts Yield improver (manufactured by Aride Colloids; Oganozob O) 0.1 part < Base paper blend 7>

Pulp; LBKP (freeness; 450 ml, c.s.f) 80 parts Pulp; DIP (freeness; 400 mCs.f) 20 parts Calcium carbonate (Okutama Kogyo; TP-121) 10 parts Neutral rosin sizing agent (manufactured by Nippon PMC; CC_167) 0.4 part Aluminum sulfate 1.4 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Caycol BUL) 0.02 parts amphoteric starch (manufactured by NSC Japan; C ato 3210) 1.0 part Dye (manufactured by BASF; "Sazo" Ruha ', Yoretto 57 L) 0 00096 parts Retention enhancer (manufactured by Aridoco Pid; Percoll 57) 0.025 parts Retainer Organozob O) 0.1 part, 0.3% slurry of the above formulation, with a paper width of 1,300 mm, papermaking speed of 150 m / min., With a fourdrinier paper machine, basis weight of 78.4 g / m Moisture 5.0% base paper was produced and used as base paper for size press.

Next, ink-jet recording papers of Examples and Comparative Examples were prepared according to the following method.

Example 1

Size press is performed on the base paper 2 prepared above with the following composition, and the solid content 3.0 g / m ² of ink jet recording paper was obtained, and was used as the ink jet recording paper of Example 1. The ash content of base paper 2 was 8.9%.

<1 formulation of size press liquid>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (manufactured by Hymo Corporation; SC-600G2) 3 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Keicoll BRAL) 0.5 part Cationic surface 0.1% of coloring pigment (manufactured by Dainichi Seika Kogyo Co., Ltd .; TB 536 blue) 0.004 parts Color pigment (manufactured by Dainichi Seika Kogyo Co., Ltd.) Manufactured; TB 1548 Violet) 0.003 parts Water 93.393 parts Example 2

The ink jet recording paper of Example 2 was produced in the same manner except that the composition of the size press liquid used in Example 1 was changed to the composition of the size press liquid 2.

<2 formulations of size press liquid>

Oxidized starch (Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (Hymo Co .; SC-600G2) 3 parts Fluorescent whitening agent (Nippon Soda Co., Ltd .; Caycol BRAL) 1.0 part Cation surface 0.1% of coloring pigment (manufactured by Dainichi Seika Kogyo Co., Ltd .; TB 536 blue) 0.004 parts Color pigment (manufactured by Dainichi Seika Kogyo Co., Ltd.) Manufactured; TB 1548 violet) 0.003 parts Water 92. 893 parts Example 3

An ink jet recording paper of Example 3 was produced in the same manner except that 1 composition of the size press liquid used in Example 1 was changed to 3 compositions of the size press liquid.

<3 size press liquids>

Oxidized starch (Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (Hymo Co .; SC-600G2) 3 parts Fluorescent whitening agent (Nippon Soda Co., Ltd .; Caycol BRAL) 1.5 parts Cationic surface Sise, agent (manufactured by BASF; /, "Sof. Last 265D) 0.1 part Colored pigment (manufactured by Dainichi Seika Kogyo; TB 536 blue) 0.004 parts Colored pigment (manufactured by Dainichi Seika Kogyo; TB 1548 Violet) 0.003 parts Water 92.393 parts Example 4

An ink jet recording paper of Example 4 was produced in the same manner except that 1 composition of the size press liquid used in Example 1 was changed to 4 compositions of the size press liquid.

4 size press liquids>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (manufactured by Himo Co .; SC-600G2) 3 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Caycol BRAL) 2.0 parts Cation Surface sizing agent (manufactured by BASF; /,, Sof. Last 265D) 0.1 part Color pigment (manufactured by Dainichi Seika Industries Co., Ltd .; TB 536 blue) 0 004 parts Color pigment (manufactured by Daisei Kagaku Co., Ltd.) Manufactured; TB 1 548 Violet) 0 003 parts Water 9 893 parts Example 5

The ink jet recording paper of Example 5 was produced in the same manner except that the base paper 2 used in Example 1 was used as the base paper 1. The ash content of the base paper 1 was 17.3%.

Example 6

An ink jet recording paper of Example 6 was produced in the same manner except that 1 composition of the size press liquid of Example 1 was changed to 5 compositions of the size press liquid.

<5 size press liquids>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (manufactured by Himo Co .; SC-600G2) 0.75 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; 0.2 g) Cationic surface size, agent (manufactured by BASF; Ha, Sof. Last 265D) 0.1 part Color pigment (manufactured by Dainichi Seika Kogyo; TB 536 blue) 0.004 part Color pigment (Dainichi Seika Company: TB 1548 Violet) 0.003 parts Water 95.893 parts Example 7 The inkjet recording paper of Example 7 was produced in the same manner except that the base paper 2 used in Example 4 was used as the base paper 6. The ash content of the base paper 6 was 17.5%.

Example 8

The ink jet recording paper of Example 8 was produced in the same manner except that the base paper 2 used in Example 1 was used as the base paper 7. The ash content of the base paper 1 was 9.3%.

Example 9

Ink jet recording paper of Example 9 was produced in the same manner except that 1 composition of the size press liquid of Example 1 was changed to 6 compositions of the size press liquid.

<6 formulation of size press liquid>

Oxidized starch (Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (Hymo Co., Ltd .; SC-600G2) 3 parts Fluorescent whitening agent (Nippon Soda Co., Ltd .; Caycol BRAL) 0.5 part Cationic surface Dye (Sumitomo Chemical Co., Ltd .; Sumireitos Bra Blue) 0.12 Dye (Sumitomo Chemical Co., Ltd .; Sumireitos Bra Violet) 0.003 parts Water 93.395 parts Example 10

An ink jet recording paper of Example 10 was produced in the same manner except that 1 composition of the size press liquid of Example 5 was changed to 7 compositions of the size press liquid.

<7 size press liquids>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (manufactured by Himo Co .; SC-600G2) 3 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Kaikol BRAL) 0.5 part Cationic surface Example 1 1 1 part water 93.4 parts water (manufactured by BASF; Huff. Last 265D)

An ink jet recording paper of Example 11 was prepared in the same manner as in Example 1, except that 1 composition of the size press liquid was changed to 8 compositions of the size press liquid.

<8 formulations of size press liquid> Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (manufactured by Hymo; SC-600G2) 3 parts Fluorescent whitening agent (commercially available triazole derivative) 1.0 part Cationic surface size (Manufactured by BASF; /,, Sof. Last 265D) 0.1 part Color pigment (manufactured by Dainichi Seika Kogyo; TB 536 blue) 0.004 part Color pigment (manufactured by Dainichi Seika Kogyo; TB 1548 Biorette) 0.003 parts Water 92.893 parts Comparative Example 1

Size press was performed on the base paper 3 prepared above with one size press solution to obtain an ink jet recording paper having a solid content of 3.0 g Zm ² , which was designated as inkjet recording paper 1 of Comparative Example 1. The ash content of base paper 3 was 5.9%.

Comparative Example 2

Inkjet recording paper of Comparative Example 2 was produced in the same manner except that base paper 3 used in Comparative Example 1 was used as base paper 4. The ash content of the base paper 4 was 9.3%.

Comparative Example 3

Ink jet recording paper of Comparative Example 3 was produced in the same manner except that the base paper 3 used in Comparative Example 1 was used as the base paper 5. The ash content of base paper 5 was 13.0%.

Comparative Example 4

An ink jet recording paper of Comparative Example 4 was produced in the same manner except that 1 composition of the size press liquid used in Example 1 was changed to 8 compositions of the size press liquid.

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3.5 parts Cationic polymer fixing agent (manufactured by Hymo; SC-600G2) 3 parts Cationic surface size, agent (manufactured by BASF; c, f). Last 265D) 0.1 part Color pigment (Dainichi Kagaku Kogyo; TB 536 blue) 0.004 parts Color pigment (Dainichi Kagaku Kogyo; TB 1548 Violet) 0.003 part Water 93.393 parts Comparative example Five

In the same manner as in Comparative Example 5, except that the base paper 2 used in Comparative Example 4 was used as the base paper 1. Ett recording paper was prepared.

Comparative Example 6

The base paper 2 produced as described above was subjected to size press with the following composition to obtain an ink jet recording paper having a solid content of 3.0 g / m ² , which was used as the ink jet recording paper of Comparative Example 6.

<9 formulations of size press liquid>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 6 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Keikol BRAL) 0.5 part Cationic surface size, agent (manufactured by BASF, Inc .; Last 265D) 0.1 part Color pigment (Dainichi Kagaku Kogyo; TB 536 blue) 0.004 parts Color pigment (Dainichi Kagaku Kogyo; TB 1548 Violet) 0.003 part Water 93.393 parts Comparative Example 7

Hewlett-Packard's “B r i g h t

White "was purchased, and Comparative Example 7 was used.

Comparative Example 8

A comparative example 8 was obtained by purchasing “PB paper”, which is both Canon's electrophotographic and ink jet paper commercially available in Japan.

With respect to the recording papers of Examples 1 to 11 and Comparative Examples 1 to 8 produced as described above, the ISO whiteness and the fluorescence intensity of the papers were measured by the evaluation methods described below. Table 1 shows the results.

1) ISO whiteness

The measurement sample was conditioned for 24 hours in an environment of 20 ° C and 65% RH. Then, the sample was subjected to ISO The whiteness was measured. The measurement was performed using ten test pieces, and the average value of the front and back surfaces of the test pieces was defined as the Iso whiteness. In the case of full color printing, when outstanding whiteness is required, it is preferable that the ISO whiteness is 95% or more.

2) Fluorescence intensity The test sample was humidified in an environment of 20 ° C and 65% RH for 24 hours, and then UV cut filter using PF_10 manufactured by Nippon Denshoku Industries Co., Ltd. using a xenon flash lamp as a light source according to JISP-8148. The ISO whiteness was measured for the case with and without. The fluorescence intensity is expressed as the difference between the ISO whiteness without using a UV cut filter and the ISO whiteness when using a UV cut filter. The measurement was performed using ten test pieces, and the average value of the front and back surfaces of the test pieces was defined as the fluorescence intensity. For paper used in everyday life, the fluorescence intensity is preferably 7 to 15%.

The inkjet suitability was evaluated by the evaluation method described below. Table 1 shows the results.

1) Image water resistance

Characters and rising lines were printed with a Canon Inkjet Printer BJ-420J, and a drop of distilled water was dropped with a No. 15 syringe needle on the printed area, and after standing to dry, the degree of bleeding was visually observed. Was evaluated. As evaluation criteria, A: good characteristics, B: good in practically acceptable range, C: practical problem, D: poor characteristics.

2) Print density

A black solid pattern was printed using an ink jet printer BJ-420J manufactured by Canon Inc., and after being allowed to dry, the optical density was measured with a Macbeth densitometer. As a criterion for evaluation, a concentration of 1.2 or more is practically preferable.

3) Image reproducibility

Prints N1 and N4 images of high-definition digital standard image data conforming to JIS X-9201 published by the Japan Standards Association with an ink jet printer BJ-420J manufactured by Canon Inc. The difference in hue value from the attached print sample was evaluated. In N1, the change in the skin color of the highlights on the woman's face and palms, and the color balance in a grayish background, and in N4, the tone and neutral color of the bright parts of the metal tableware and glass are reproduced. The evaluation was performed with emphasis on gender. The evaluation criteria were as follows: A: good characteristics, B: good in practically acceptable range, C: practical problems, D: poor characteristics. Iso Whiteness Fluorescence intensity Image density Water resistance Image

Reproducibility

(%) (%)

Example 1 98.8 8.1 1.35 AA Example 2 100.6 9.4 1.35 AA Example 3 101.0 9.9 1.35 AA Example 4 101.2 10.2 1. 34 AA Example 5 100.3 9.2 1.38 AA Example 6 95.2 7.3 1.32 BB Example 7 102.5 14.8 1.33 AA Example 8 96.5 8.3 1.30 AB Example 9 98.2 8.2 1.34 AA Example 10 97.0 9.7 1.37 AB Example 11 95.2 7.5 1.24 BA Comparative Example 1 93.67 5 1.25 AC Comparative Example 2 94.1 7.4 1.25 AC Comparative Example 3 92.8 7.5 1.28 AC Comparative Example 4 90.3 2.8 1.24 AD Comparative Example 5 92. 5 0.3 1 30 AD Comparative Example 6 98. 6 9. 0 1.25 DA Comparative Example 7 107. 0 1 3.0 1. 15 DA Comparative Example 8 84. 5 0.2 3 1.33 DC Above Considering the evaluation results, as is clear from Examples 1 to 6, in order to obtain good image density and image reproducibility, the ISO whiteness should be 95% or more and the fluorescence intensity should be 7% or more. Is necessary. From Example 7, it can also be seen that even if the fluorescence intensity is increased to near 15%, the image density and image reproducibility are saturated. In Example 9, not only a pigment but also a dye could be used as a colorant in the size press composition. In Example 10, there was no problem even if a dye or pigment was not used in the size press liquid. It can be seen that many types of fluorescent whitening agents can be used. As is clear from Comparative Examples 1 to 5, it can also be seen that the image reproducibility deteriorates only when the characteristics of the ISO whiteness and the fluorescence intensity do not meet either of the standards. Further, as shown in Comparative Example 6, when the cationic fixing agent was not applied, the water resistance was greatly deteriorated. Example 12: I 6

For the purpose of clarifying the features of the second invention by the combination, Papers 8-12 were made.

Pulp; LBKP (freeness; 450 ml, c.s.f) 100 parts Calcium carbonate (Okutama Kogyo Co., Ltd .; TP-121) 26 parts Neutral mouth gin sizing agent (0 bottles PMC Co .; CC- 167) 0.4 part Aluminum sulfate 1.4 part Amphoteric starch (NSC Japan; Cat 3210) 1 part Dye (C, 'Sasso'-Luha' sorbet 57 L; BASF) 0 00096 parts Retention improver (Manufactured by Allite® Conid; Percoll 57) 0.025 parts Retention improver (manufactured by Allide Colloid; Organosorb o) 0.1 part

Pulp; LBKP (freeness; 450 ml, c.s.f) 100 parts Calcium carbonate (Okutama Kogyo; TP-1 21) 32 parts Neutral rosin sizing agent (Nippon PMC; CC-167) 0 4 parts Aluminum sulfate 1.4 parts Optical brightener (Nippon Soda Co., Ltd .; Keikol BUL) 0.02 parts Amphoteric starch (NSC Japan; Cat 3210) 1.0 parts Dyes "Yoretto 57 L; manufactured by BASF) 0 00096 parts Retention improver (Allite ', manufactured by Co Pid; Parco 57) 0. 030 parts Retention improver (Allite manufactured by Colloid; Organozob O) 0 . 1 5 parts <Base paper mix 10>

Pulp; LBKP (freeness; 450 ml, csf) 100 parts Calcium carbonate (Okutama Kogyo; TP-1 21) 21 parts Neutral rosin sizing agent (Nippon PMC; CC-167) 0. 4 parts Aluminum sulfate 1.4 parts Amphoteric starch (NSC, Japan; Cat 3210) 1.0 part Dye (Sasa-Ruha, Yoretto 57 L; BASF) 0 00096 parts Retention improver (Allite) "Co Poid Co., Ltd .; Percoll 57) 0.025 parts Yield enhancer (Allide Colloid Co .; Organosorb O) 0.1 part Glue paper mix 1 1>

Pulp; LBKP (freeness; 450 ml, c.s.f) 100 parts Calcium carbonate (Okutama Kogyo; TP-121) 1 1 Neutral rosin sizing agent (Nippon PMC; CC_ 1 6 7) 0.4 part Aluminum sulfate 1.4 Part Fluorescent whitening agent (manufactured by S-Soda Co., Ltd .; Keikol BUL) 0.0 2 part Amphoteric starch (manufactured by NSC Japan, Cat. 3 210) 1. 0 parts Dye (Cha-Sasso-Ruha) 5.7 L; manufactured by BASF 0 000 96 parts Retention improver (manufactured by Aridoco Pid; Percoll 57) 0.0 25 parts Retention improver (Aridoco pid) Company; Organozob o) 0.1 parts

Panolep; LBKP (freeness; 450 ml, c.s.f) 100 parts Calcium carbonate (Okutama Kogyo; TP-121) 6 parts Neutral rosin sizing agent (Nippon PMC; CC- 1 67) 0.4 part Aluminum sulfate 1.4 part Fluorescent whitening agent (Nippon Soda Co., Ltd .; Keikol BUL) 0.0 2 parts Amphoteric starch (NSC Japan; Cat 3210) 1.0 part Dyes ("Sasso" -Ryoretto 57 L; BASF) 0 000 96 parts Retention improver (manufactured by Aridoco Pid; Percoll 57) 0.0 25 parts Retention improver (manufactured by Aridocolloy; Organosorb O) ) 0.1 part 0.3% slurry of the above composition was prepared with a fourdrinier paper machine at a machine width of 1,300 mm and a papermaking speed of 150 m / min, with a basis weight of 78.4 g / m and a water content of 5.0%. Base paper was made and used as base paper for size press.

Next, the ink jet recording paper of the example was produced according to the following method. Example 1 2

The base paper 11 prepared as described above was subjected to size press with one composition of the size press liquid to obtain an ink jet recording paper having a solid content of 3.0 g / m ² , which was used as the ink jet recording paper of Example 12. The ash content of the base paper 11 was 8.9%.

Example 13 Inkjet recording paper of Example 13 was produced in the same manner except that base paper 11 used in Example 12 was used as base paper 10. The ash content of the base paper 10 was 17.2%.

Example 14

The ink jet recording paper of Example 14 was produced in the same manner except that the base paper 11 used in Example 12 was changed to the base paper 8. The ash content of base paper 8 was 19.7%. Example 15

The ink jet recording paper of Example 15 was produced in the same manner except that the raw paper 11 used in Example 12 was changed to the raw paper 12. The ash content of the base paper 12 was 4.8%. Example 16

The ink jet recording paper of Example 16 was produced in the same manner except that the base paper 11 used in Example 12 was used as the base paper 9. The ash content of the base paper 9 was 22.3%. With respect to the recording papers of Examples 12 to 16 produced as described above, the ISO whiteness, the fluorescence intensity, and the inkjet suitability of the papers were measured by the evaluation methods described above. The surface strength was measured according to the following measurement method. Table 2 shows the results.

1) Surface strength

The measurement sample was conditioned for 24 hours in an environment of 20 ° C and 65% RH, and then a commercially available 18 mm wide cellophane adhesive tape (Nichiban, Cellotape) was applied at a linear pressure of 300 gZcm, and 1 cm / cm Judgment was made based on the amount of powder adhering to the tape when peeled at a speed of sec. The evaluation criteria are: A: little powder adheres to the tape, strong surface strength; B: powder slightly adheres to the tape, but practically no problem; C: powder adheres to the tape, depending on usage conditions Is a problem, D: Powder adheres considerably to the tape, which is a practical problem. E: A large amount of powder adheres to the tape and cannot be used. Table 2

Considering the above evaluation results, as is apparent from Examples 12 to 14, the base paper having calcium carbonate ash content of 5 to 20% as a filler was added with a fluorescent whitening agent, a water-soluble binder and a cationic high ISO whiteness measured by a measurement method specified in JISP-8148 using a coating liquid containing a molecular fixing agent as a main component and using a xenon flash lamp on the coated paper as a light source. Of 95% or more and a fluorescence intensity of 7 to 5%: I 5%, it is possible to obtain ink jet paper with high image density, not only water resistance and image reproducibility, but also excellent surface strength. You can see When the ash content of calcium carbonate exceeds 20% as in Example 16, the water resistance, the image density and the image reproducibility are improved, but the surface strength is also significantly reduced. Further, when the ash content of calcium carbonate is lower than 5% as in Example 15, the surface strength is maintained, but the water resistance, image density and image reproducibility are reduced.

Examples 17 to 22 and Comparative Examples 9 to: 10

For the purpose of clarifying the features of the third invention by the combination, base papers 13 to 14 were produced according to the following composition.

Pulp; LBKP (freeness: 450 ml, c.s.f) 100 parts Calcium carbonate (Okutama Kogyo; TP-121) 12 parts Neutral rosin sizing agent (Japan PMC; CC-167) 0. 4 parts Aluminum sulfate 1.4 parts Fluorescent whitening agent (Nippon Soda Co., Ltd .; Keiko BUL) 0.02 parts Amphoteric starch (NSC Japan; Cat 3210) 1.0 parts Dye (manufactured by BASF; Ha, Sasso "-Runo," Yoretto 57 L) 0 00096 parts Retention improver (manufactured by Aridoco π-id; Percoll 57) 0.025 parts Retention improver (manufactured by Aride Colloid; Organosorb) O) 0.1 copy

Pulp; LBKP (freeness; 450 m and c.s.f) 80 parts Pulp; DIP (freeness; 400 ml, c.s.f) 20 parts Calcium carbonate (Okutama Kogyo; TP-121) 12 parts Neutral rosin sizing agent (manufactured by PMC Japan; CC-167) 0.4 part Aluminum sulfate 1.4 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Keiko BUL) 0.02 parts amphoteric starch (NSC Japan) Cato 3210) 1.0 part Dye (manufactured by BASF; Ha, Sasso "Luha" sorbet 57 L) 0, 00096 parts Yield improver (manufactured by Alite Co-Pid; Percoll 57) 0.025 Part Yield improver (Allite, manufactured by Colloid Co., Ltd .; Organosorb O) 0.1 part 0.3% slurry of the above composition was machined with a fourdrinier paper machine at a papermaking width of 1,300 mm and a papermaking speed of 150 m / min. Base paper having an amount of 78.4 g / m ² and a water content of 5.0% was prepared and used as a base paper for size press.

Next, ink jet recording papers of Examples and Comparative Examples were produced according to the following method.

Example 17

The base paper 13 prepared as described above was subjected to size press with one mixture of the size press liquid to obtain an ink jet recording paper having a solid content of 3.0 g / m ² , which was used as the ink jet recording paper of Example 17. The ash content of the base paper 13 at this time was 10.7%. Example 18

An ink jet recording paper of Example 18 was produced in the same manner except that 1 composition of the size press liquid of Example 13 was changed to 2 compositions of the size press liquid.

Example 19

An ink jet recording paper of Example 19 was produced in the same manner as in Example 17 except that 1 composition of the size press liquid was changed to 3 compositions of the size press liquid. Example 20

An ink jet recording sheet of Example 20 was produced in the same manner as in Example 17 except that 1 composition of the size press liquid was changed to 4 compositions of the size press liquid.

Example 21

The base paper 14 prepared above was subjected to size press with one composition of the size press liquid to obtain an ink jet recording paper having a solid content of 3.0 g / m ² , which was used as the ink jet recording paper of Example 21. The ash content of the base paper 14 at this time was 10.9%. Example 22

An ink jet recording paper of Example 22 was produced in the same manner as in Example 17 except that 1 composition of the size press liquid was changed to 10 compositions of the size press liquid.

<10 size press liquids>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 5 parts Cationic polymer fixing agent (manufactured by Himo Co .; SC-600G2) 0.71 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Keiko BRAL) 0.5 part Cationic surface size, agent (manufactured by BASF; /,, Sof. Last 265D) 0.1 part Color pigment (manufactured by Daisei Kagaku Co., Ltd .; TB 536 blue) 0.004 part Color pigment (Dainichisei (Manufactured by Kogyo Co .; TB 1548 Violet) 0.003 parts Water 93.683 parts Example 23

The ink jet recording paper of Example 23 was prepared in the same manner as in Example 17 except that the cationic polymer fixing agent was changed to acrylamide-dolyallylamine copolymer in one composition of the size press liquid of Example 7. Produced.

Ku size press liquid 1 1 formulation>

Oxidized starch (Nippon Shokuhin Kako; MS 3800) 3 parts Cationic polymer fixing agent

(Commercially available acrylamide dojiarylamine copolymer) 3 parts Fluorescent whitening agent (Nippon Soda Co., Ltd .; Keicoll BRAL) 0.5 part Cationic surface size, agent (BASF Co., Ltd .; /, 'S / Last 265D) 0.1 part Color pigment (Dainichi Seika Kogyo Co., Ltd .; TB 536 blue) 0.004 part Coloring pigment (manufactured by Dainichi Seika Kogyo Co., Ltd .; TB 1548 Violet) 0.003 parts Water 93.393 parts Example 24

Example 17 The ink jet of Example 24 was prepared in the same manner except that the size press solution was changed to a dimethylamine-epiclorhydrin polycondensate in which the cationic polymer fixing agent was changed to 1 and the size press solution was changed to 1 and the mixture was changed. Recording paper was prepared.

(Commercially available dimethylamine-epiclorhydrin polycondensate) 3 parts Fluorescent whitening agent (13 Soda Co., Ltd .; Keicoll BRAL) 0.5 part Cation surface size, agent (BASF Co., Ltd .; C, SOF) Last 265D) 0.1 part Color pigment (Dainichi Kagaku Kogyo; TB 536 blue) 0.004 parts Color pigment (Dainichi Kagaku Kogyo; TB 1548 Violet) 0.003 part Water 93.393 parts Example 25

The ink jet recording paper of Example 25 was produced in the same manner as in Example 17, except that the composition of the size press liquid was changed to the triazole derivative, and the size press liquid was changed to the triazole derivative.

<13 formulations of size press liquid>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (manufactured by Hymo; SC-600G2) 3 parts Fluorescent whitening agent (commercially available triazole derivative) 1.5 parts Cationic surface size (Manufactured by BASF; c, Sof. Last 265D) 0.1 part Color pigment (manufactured by Dainichi Seika Kogyo Co., Ltd .; TB 536 blue) 0 004 parts Color pigment (manufactured by Dainichi Seika Kogyo Co., Ltd .; TB 1548 Violet) 0 003 parts Water 92.493 parts Example 26

Example 17 The optical brightener was changed to an imidazole derivative in one formulation of the size press liquid of 7 Ink jet recording paper of Example 26 was prepared in the same manner except that 14 of the size press liquids were used.

<14 size press liquids>

Oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixing agent (manufactured by Himo Inc .; SC-600G2) 3 parts Fluorescent whitening agent (commercially available imidazole derivative) 1.0 part Cation surface size (Manufactured by BASF; /,, Sof. Last 265D) 0.1 part Color pigment (manufactured by Dainichi Seika Kogyo; TB 536 blue) 0.004 part Color pigment (manufactured by Dainichi Seika Kogyo; TB 1 548 biolet) 0.003 parts Water 92.893 parts Comparative Example 9

An ink jet recording paper of Comparative Example 9 was produced in the same manner as in Example 17 except that 1 composition of the size press liquid was changed to 15 compositions of the size press liquid.

<15 press of size press liquid>

Oxidized starch (Kaihon Shokuhin Kako Co., Ltd .; MS 3800) 3 parts Cationic polymer fixative (HIMO; SC-600G2) 3 parts Fluorescent whitening agent (Nippon Soda Co., Ltd .; Caycol BRAL) 0.4 parts Cation Surface sizing agent (manufactured by BASF; /,, Sof. Last 265D) 0.1 part Color pigment (manufactured by Dainichi Seika Kogyo; TB 536 blue) 0.004 part Color pigment (Dainichi Seika Company; TB 1548 Violet) 0.003 parts Water 93.493 parts Comparative Example 1◦

An ink jet recording paper of Comparative Example 10 was produced in the same manner except that 1 composition of the size press liquid of Example 17 was changed to 16 compositions of the size press liquid.

Ku size press liquid 16 compounding>

Cationic polymer fixing agent (manufactured by Hymo; SC-600G2) 6 parts Fluorescent whitening agent (manufactured by Nippon Soda Co., Ltd .; Keicoll BRAL) 0.9 parts Cationic surface size, agent (manufactured by BASF; / ,, 'Sof. Last 265D) 0.1 part Color pigment (Dainichi Seika Kogyo Co., Ltd .; TB 536 Bullet) 0.004 part Coloring pigment (manufactured by Dainichi Seika Kogyo Co., Ltd .; TB 1548 Violet) 0.03 parts Water 92.993 parts 3 Examples 17 to 26 and Comparative Examples 9 to 10 prepared as described above. With respect to the recording paper, the ISO whiteness and the fluorescence intensity of the paper were measured according to the evaluation method described above. Table 3 shows the results.

In addition, image reproducibility and surface strength suitable for inkjet were measured according to the evaluation method described above. The image water resistance and print density were measured according to the following measurement methods. Table 4 shows the results.

1) Image water resistance

Characters and rising lines were printed with a Canon Inkjet Printer BJ-420J, and a drop of distilled water was dropped on the printed black and magenta portions with a No. 15 syringe needle, left to dry, and then spread. Was visually evaluated. The evaluation criteria were as follows: A: good characteristics, B: good in practically acceptable range, C: practical problems, D: poor characteristics.

2) Print density

Four full-color solid patterns were printed using an ink jet printer BJ-420J manufactured by Canon Inc., and after being allowed to dry, the optical densities of black and magenta were measured with a Macbeth densitometer. As a criterion for evaluation, a concentration of 1.2 or more is preferable in practical use.

Table 3

Fluorescent whitening agent Cationic Iso whiteness Fluorescence intensity Polymer fixing agent

Type Blending amount Type Blending amount (%) (%) Example 17 ① 0.5 ① 3.0 99.0 0 8.1 Example 18 ① 1. 0 ① 3. 0 100. 89.5 Example 19 ① 1. 5 ① 3.10 101. 39.9 Example 20 20 1. 2. 1 ① 3.0 101.5. 10.3 Example 21 ① 1. 0 ① 3. 0 98.8.9.6 Example 22 ① 0. 5 ① 0. 71 99. 48.7 Example 23 ① 1. 0 ② 3. 0 101. 19.8 Example 24 24 ① 1. 0 ③ 3.0 0 100. 59.3 Example 25 2 1. 0 1 3. 0 95. 8 7. 7 Example 26 3 1. 0 1 3. 0 95. 1 7. 4 Comparative example 9 1 0. 4 1 3. 0 93. 9 5. 6 Compare Example 10 (1) 0.9 (1) 0.90 (6) 6.8 6.8 Optical brightener: diaminostilbene-disulfonic acid derivative

②Triazole derivative, ③Imidazole derivative Cationic polymer fixing agent:

①Polyvinyl alcohol-cation monomer-graft polymer

(2) Acrylamide dojiallylamine copolymer

③ Dimethylamine-epichlorohydrin polycondensate

Table 4

Image density image AS aqueous image Surface strength

BLACK MAGENTA BLACK MAGENTA Reproducibility Example 17 1.35 1.20 AAAA Example 18 1.35 1.21 AAAA Example 19 1.35 1.21 AAAA Example 20 1.34 1.20 ABAA Example 21 1 30 1.20 Example of AAAA 22 1. 30 1.19 Example of CCBA 23 1 .25 1.20 Example of BCAA 24 1 .28 1.21 Bc Example of AA 25 1. 27 1.19 Example of ABBA 26 1.25 1.18 ABBA Comparative Example 9 1.28 1.17 CDCA Comparative Example 10 1.34 1.20 AACD Considering the above evaluation results, as is apparent from Examples 17 to 20, the fluorescent whitening agent of the coating liquid is a diaminostilbene-disulfonic acid derivative (A), and the cationic polymer fixing agent Is a polyvinyl alcohol-cationic monomer graft polymer (B), and the ISO whiteness and the fluorescence intensity are high when the mixing ratio A: B of the solid content is in the range of 1: 6 to 2: 3. Excellent in image density and water resistance in inkjet suitability. However, as seen in Comparative Example 9, when the concentration of the fluorescent whitening agent is low and deviates from the above range, not only the ISO whiteness but also the fluorescence intensity is greatly reduced. As shown in Comparative Example 10, this phenomenon occurs even when the concentrations are high, because the fluorescent brightener is deactivated by the cationic group of the fixing agent, and the same phenomenon occurs. In Example 22, on the contrary, the concentration of the cationic polymer fixing agent was low and was out of the above range, but at this time, the water resistance started to deteriorate. Further, in Examples 23 and 24, the type of the optical brightener is changed, but in this case, the balance between the image density and the water resistance is slightly lost. In Examples 25 and 26, the kind of the cationic polymer fixing agent was changed, but the ISO whiteness and the fluorescence intensity tended to decrease, and the image density also began to deteriorate. These results indicate that the fluorescent whitening agent is a diaminostilbene monodisulfonate derivative, the cationic polymer fixing agent is a combination of polyvinyl alcohol, a cationic monomer, and a graft polymer. It is clearly shown that by setting the mixing ratio A: B within the range of 1: 6 to 2: 3, the most preferable ink jet paper for ISO whiteness, fluorescence intensity, and ink jet suitability can be obtained.

Industrial applicability

The ink jet recording paper of the present invention is an ink jet recording paper obtained by applying a coating liquid mainly containing a water-soluble binder and a cationic polymer fixing agent to a neutral base paper mainly made of wood pulp, and The xenon flash lamp of the coated paper is used as the light source, the ISO whiteness is 95% or more, and the fluorescence intensity is 7 to 15 as measured by the measurement method specified in JISP-8148. %, The ISO whiteness of the paper is increased, and despite being a plain paper type ink jet recording paper, the image density and color reproducibility of the recorded image are excellent, and the printing An ink jet recording sheet having water resistance can be provided. In the second invention, the base paper ash content according to JISP-8126 is less than 20% except that calcium carbonate is used as a filler under the above conditions, and the incineration treatment is performed at 500 ° C. for 4 hours. By combining the following features, it is possible to provide an ink jet recording sheet having a high surface strength while maintaining the above-described ink jet characteristics.

In the third invention, the fluorescent whitening agent (A) in the coating solution is used for the diaminostilbene-disulfonic acid derivative, and the cationic polymer fixing agent (B) is used for the polyvinyl alcohol-monocationic monomer graft polymer. By specifying that the mixing ratio A: B of the solid coating amount is in the range of 1: 6 to 2: 3, the ISO whiteness is high, the surface strength is high, and the recorded image It is possible to provide an ink jet recording sheet which is excellent in image density and color reproducibility and has water resistance of a printing portion.

Claims

The scope of the claims

1. An ink jet recording paper obtained by applying a coating solution containing a fluorescent whitening agent, a water-soluble binder, and a cationic polymer fixing agent to neutral base paper made mainly of wood pulp, In addition, using a coated paper xenon flash lamp as the light source, the ISO whiteness measured by the measurement method specified in JISP-8184 is 95% or more, and the fluorescence intensity is 7 to 15 % Inkjet recording paper.

2. In the ink jet recording paper according to claim 1, JISP — 812 except that the neutral base paper is made using calcium carbonate as a filler, and the ashing process is performed at 500 ° C. for 4 hours. Inkjet recording paper with a base paper ash content of 5 to 20% according to 6.

3. The ink jet recording paper according to claim 1, wherein the fluorescent whitening agent of the coating solution is a diaminostilbene-disulfonic acid derivative (A), and the cationic polymer fixing agent is a polyvinyl alcohol-monothione monomer. Inkjet recording paper which is a graft polymer (B) and has a mixing ratio of solid coating amount A: B force 1: 6 to 2: 3.

4. The ink jet recording paper according to claim 1, wherein the coating liquid is applied using an on-machine size press of a paper machine.

5. The ink jet recording paper according to claim 1, wherein the wood pulp contains waste paper pulp.